This invention has relation to wheeled undercarriages which can be easily and conveniently mounted to snowmobiles after the endless track drive assembly of the snowmobile has been removed thus to allow the snowmobile body and its engine and steering mechanism to be utilized in an over-the-road or all-terrain wheeled vehicle. The invention presents a wheeled undercarriage conversion kit which is adaptable to reversibly convert any one of a large number of different sizes and models and makes of snowmobiles to over-the-road operation.
It is not new broadly to convert a snowmobile having a body and an endless track drive mechanism mounted in a downwardly opening tunnel inside of the body for use on wheels. See U.S. Pat. No. 3,480,096 granted in November of 1969 to Hammitt. In this patent, however, the snowmobile track means and the other elements of the endless drive track assembly are left undisturbed, and a rear wheel drive axle is extended outwardly from the rear sprocket axle of the snowmobile. At the front end, the entire ski and vertical spindle mounting the ski are removed and a separate spindle, mounting a front steering wheel, is replaced in a special construction which is useful, of course, only on a machine built for the specific conversion shown in Hammitt. This structure would be of no value whatever in converting any one of a very large number of ordinary snowmobiles, built only for snowmobile action, into over-the-road vehicles.
Apparatus for converting from over-the-road to over-the-snow operation and back again is also shown in U.S. Pat. No. 3,370,665, granted in February of 1968 to Stanaback. In this structure, however, a tandem axle over-the-road vehicle is converted for operation over the snow by the expedient of attaching endless snow traction drive belts over each set of tandem wheels.
Other patents which disclose conversions of snowmobiles for over-the-road operation include U.S. Pat. Nos. 3,521,719, granted July 28, 1970 to Coons; 3,664,447, granted in May of 1972 to Kane; and 3,774,706, granted in November of 1973 to Kiekhaefer. Each of these structures, however, contemplates a substantial complete rebuilding and modification of the underside and interior works of the snowmobile to accommodate the frame and wheel structures. It is evident that the structure of each of these patents must be adapted to a particular model, size and make of snowmobile in order to be effective. None presents a kit which can be substantially universally utilized to convert most if not all of the snowmobiles on the market today to effective over-the-road action and back again utilizing only the two ski mounting brackets on the front of the snowmobile, one transversely extending positioning shaft across a forward portion of the snowmobile tunnel, and two suspension spring assemblies from the rear of the snowmobile body to a frame supporting the two rear over-the-road wheels.
U.S. Pat. Nos. 712,196, l granted in October of 1902 to Lane et al and 2,692,778 granted in October of 1954 to Stump show the use of triangular frames to support vehicle wheels for a rocking axle suspension. Each of these patents discloses, however, simply an over-the-road motor vehicle. No concept of how to utilize a triangular frame to obtain a rocking action with respect to rear wheels on a replaceable wheeled undercarriage under a snowmobile while still resiliently supporting the rear portion of the snowmobile is shown or suggested.
U.S. Pat. No. 2,675,247 granted in April of 1954 to Meng shows four independent wheel suspensions on a vehicle chassis of a regular motor vehicle. It does not show or suggest any way of adapting such a structure to use on a wheeled undercarriage for converting snowmobiles either.
A suspension and drive mechanism for endless tread vehicles in which the right tread is independent in suspension from the left tread is shown in U.S. Pat. No. 2,967,578 granted in January of 1961 to Schomers. However, the front and rear wheels on either side of the structure are not independent from each other, so four wheel flexibility over uneven terrain is not obtainable by using the structure shown in this patent or any structure suggested by it.
U.S. Pat. No. 3,623,563 granted in November of 1971 to Gostomski shows a particular structure resiliently mounting the skiis to the front end of a snowmobile and provides a plate for attaching the ski to the bottom of the suspension mechanism. A front steering wheel is provided with a matching attachment so that it can be substituted for the ski. Obviously the teaching of this patent is only useful in connection with one particular kind of ski mounting and a matching, identical kind of front wheel mounting. It is in no way adaptable to use with a conversion kit which will allow a wheeled undercarriage to be used to adapt many kinds of snowmobiles for over the road operation.
U.S. Pat. Nos. 3,847,239, granted in November of 1974 to Copeland, 3,825,086, granted in July of 1974 to Bombardier and 3,882,948, granted in May of 1975 to Southiere disclose snowmobile steering mechanisms which have a steering geometry to reduce skidding when the snowmobile takes a corner. This structure, however, is only the starting point for the structure disclosed in the present application. For example, in the patent to Southiere, the spring couplers 58,68 which connect to the leaf springs 55, 65 of the skiis are equivalent to ski-mounting brackets 30,32 of the present invention; and horizontal pins 59,69 of Southiere are equivalent to deadbolt 40 and ski rocker pin 48 in the present specification. To disable the steering mechanism of the Southiere patent, in the manner subsequently called for in this specification, tie rod 122 of Southiere could be removed, for example.
Other patents which were located during a preliminary search of the present invention are:
U.S. Pat. No. 3,414,290 granted in December of 1968 to Wilfert et al; and
U.S. Pat. No. 1,192,081 granted in July of 1916 to Loxley et al.
These patents are believed to be at least somewhat pertinent.
Applicant is aware of no further pertinent prior art.